1. Field of the Invention
The invention relates to power supplying apparatus and method which can suppress an electric power in what is called a standby mode.
2. Description of the Related Arts
In recent years, a standby mode is provided for a power supplying apparatus, for example, an AC adapter in correspondence to a case where a personal computer or a cellular phone (hereinafter, they are generally referred to as an electronic apparatus) is not connected or, even if it is connected, a power source is hardly consumed. The AC adapter is switched from the standby mode to a supply mode for outputting (consuming) the power source or from the supply mode to the standby mode. At this time, in the standby mode, the operation with a suppressed electric power consumption is performed.
In the standby mode, a signal is transmitted from the secondary side to the primary side and, in the supply mode, the signal which is transmitted from the secondary side to the primary side is stopped. This is because if the signal which is transmitted from the secondary side to the primary side is not transmitted due to some erroneous operation, by operating in the supply mode, a higher safety can be assured.
In recent years, in case of transmitting a signal from the secondary side to the primary side of a transformer, a photocoupler has been used as an example of a feedback circuit whose insulation is held. For example, as shown in FIG. 1, two signals are transmitted from a secondary power source unit 252 to a primary power source unit 251, that is, from the secondary side to the primary side, through photocouplers 253 and 254, respectively. When there are two or more kinds of signals which are transmitted from the secondary side to the primary side as mentioned above, the photocoupler is used in correspondence to each signal.
For example, there is a problem such that in the case where the signal which is transmitted from the secondary side to the primary side is stopped in the standby mode and the signal is transmitted from the secondary side to the primary side in the supply mode, if the signal which is transmitted from the secondary side to the primary side is not transmitted due to some erroneous operation, the operating mode is never set to the supply mode.
However, there is a problem such that an electric power consumption in the standby mode increases due to the photocoupler through which the signal to suppress the electric power consumption is transmitted from the secondary side to the primary side through the photocoupler in the standby mode.
However, since a shape of the photocoupler does not become small, there is a problem such that by using a plurality of photocouplers, a shape of a package of those photocouplers increases.
Further, there is also a problem such that since the signal is transmitted through a portion in an insulated state, if many photocouplers are used, the safety deteriorates.
It is, therefore, the first object of the invention to provide power supplying apparatus and method which can sufficiently suppress an electric power consumption in the standby mode and supply a power source at a predetermined interval.
The second object of the invention is to provide power supplying apparatus and method which can transmit two or more kinds of signals from the secondary side to the primary side by one photocoupler.
According to the first aspect of the invention, there is provided a power supplying apparatus whose primary side and secondary side are insulated, comprising: detecting means for detecting a mode of the secondary side; signal transmitting means for transmitting a detection result of the detecting means to the primary side in the insulated state; and control means for switching a power generating mode and a power stop mode in accordance with the detection result received through the signal transmitting means, wherein the apparatus is controlled so that an operating mode is set to the power generating mode when there is a signal which is transmitted through the signal transmitting means and the operating mode is set to the power stop mode when there is not the signal which is transmitted through the signal transmitting means, and when the power stop mode continues for a long period of time, it is changed to the power generating mode.
According to the second aspect of the invention, there is provided a power supplying apparatus which can perform an intermittent oscillation to suppress an electric power consumption, wherein a primary side has: time constant means which is set to a period longer than a period of the intermittent oscillation; signal transmitting means for transmitting a signal from a secondary side; and switching means for controlling the apparatus so as to perform the intermittent oscillation in response to the received signal, and the secondary side has detecting means for detecting a state of a load which is connected.
According to the third aspect of the invention, there is provided a power supplying method for a power supplying apparatus whose primary side and secondary side are insulated, comprising the steps of: detecting a mode of the secondary side; transmitting a detection result to the primary side in the insulated state; switching a power generating mode and a power stop mode in accordance with the transmitted and received detection result; controlling so that the power generating mode is set when there is a signal which is transmitted through signal transmitting means and the power stop mode is set when there is not the signal which is transmitted through the signal transmitting means; and changing the power stop mode to the power generating mode when the power stop mode continues for a long period of time.
According to the fourth aspect of the invention, there is provided a power supplying method which can perform an intermittent oscillation to suppress an electric power consumption, wherein on a primary side, a time constant is set to a period longer than a period of the intermittent oscillation, a signal which is transmitted from a secondary side is received, and a switching operation is performed so that the intermittent oscillation is performed in response to the received signal, and on the secondary side, a voltage and a current which are outputted are rectified, the voltage and/or the current which are/is outputted are/is detected, the signal is transmitted to the primary side, and the signal to be transmitted is controlled on the basis of the detected voltage and/or the detected current.
As mentioned above, to suppress the electric power consumption, the signal is transmitted in the case where the voltage and/or current which are/is used when the signal is transmitted from the secondary side to the primary side are/is smaller than a reference value(s). By setting the time constant set so as to become the period longer than that of the intermittent oscillation, a power source can be outputted even if the signal which is transmitted from the secondary side to the primary side cannot be transmitted.
According to the fifth aspect of the invention, there is provided a power supplying apparatus whose primary side and secondary side are insulated, comprising: detecting means for detecting a voltage and/or a current of the secondary side; synthesizing means for synthesizing at least two voltages and/or currents; signal transmitting means for transmitting a synthesized synthesis signal to the primary side in the insulated state; separating means for separating at least the two voltages and/or currents from the transmitted and received synthesis signal; and control means for controlling the operation of the primary side in accordance with each of at least the separated two voltages and/or currents.
According to the sixth aspect of the invention, there is provided a power supplying method for a power supplying apparatus whose primary side and secondary side are insulated, comprising the steps of: detecting a voltage and/or a current of the secondary side; synthesizing at least two voltages and/or currents; transmitting a synthesized synthesis signal to the primary side in the insulated state; separating at least the two voltages and/or currents from the transmitted and received synthesis signal; and controlling the operation of the primary side in accordance with each of at least the separated two voltages and/or currents.
According to the seventh aspect of the invention, there is provided a power supplying method for a power supplying apparatus whose primary side and secondary side are insulated, comprising the steps of: detecting a voltage and/or a current of the secondary side; synthesizing at least two voltages and/or currents; transmitting a synthesized synthesis signal to the primary side in the insulated state; separating at least the two voltages and/or currents from the transmitted and received synthesis signal; and switching a power generating mode and a power stop mode in accordance with each of at least the separated two voltages and/or currents.
The synthesis signal obtained by synthesizing at least the two signals (voltages and/or currents) is transmitted and the transmitted synthesis signal is received and, thereafter, the signal can be separated. The power generating mode and the power stop mode can be switched and controlled in accordance with the separated signals. Therefore, the signal can be transmitted by the small number of circuits.
The above and other objects and features of the present invention will become apparent from the following detailed description and the appended claims with reference to the accompanying drawings.